Answer: B.They are arranged in energy levels
Explanation: Electrons orbit around the nucleus of an atom, and are not spread around equally throughout an atom because there are a different amount of electrons that can fit in each energy level or electron shell (both are the same thing). For example the first energy level can hold up to 2 electrons, the second shell can hold up to 8 electrons, the third can hold up to 18, and so on represented by the equation 2(n^2)
Answer: The correct option is C.
Explanation: Beta minus (
) decay is the decay in which a neutron is converted into proton and releases beta particle or generally known as electron.
There is an increase in the Atomic number because one protons is being formed.
In the case of beta-minus decay of phosphorous, the P-nucleus gets changed to Sulfur nucleus. The balanced Chemical equation for this process is:

Hence, the correct option is C.
Answer:
Explanation:
The density of pure lead is 10.49g/cm³
Given parameters:
Volume of water displaced by the crown = 238.1ml
Mass of crown = 2.50kg
Solution
We would simply find the density of the discovered crown and compare with that of the standardized density of lead.
Density is an intensive property of matter and it is the same for any form of matter. It is amount of substance per unit volume:
Density = 
We need to convert the given parameters to standard unit,
1ml = 1cm³
Therefore, the volume of water displaced is 238.1cm³
Also,
1kg = 1000g
2.5kg = 2500g
mass of the crown is 2500g
Density =
= 10.49g/cm³
The crown is made of silver because the density matches with that of pure silver.
Life Span. The life span of damselflies varies between species and within species depending on environmental factors. After one to three weeks, the eggs, laid in water, usually hatch, releasing the larvae or nymphs, but eggs laid in late summer may overwinter before hatching.
The universe moves with the energy left off from the big bang. This is why the universe constantly expands.
Things rotate and revolve because of gravity.
Hope this helped!